1. Field of the Invention
The present invention relates to a high-voltage semiconductor device, and more particularly, to a high-voltage semiconductor device integrating a high-voltage metal-oxide-semiconductor transistor with an electrostatic discharge protection device.
2. Description of the Prior Art
Current electrical power systems provide an alternating current having a variety of frequencies ranging from 50 to 60 Hz, and a voltage ranging from 100 volts to 240 volts, and with the differences of the electrical devices, operating voltage and frequencies also different. Thus, in order to provide a voltage corresponding to the operating voltage range of an electrical device, electrical device generally has a power conversion circuit disposed therein or at the outside thereof to electrically connect to the electrical power system, and a high voltage generated by the electrical power system can be reduced by the power conversion circuit to be corresponding to the operating voltage range of an internal circuit in the electrical device.
An input end of the power conversion circuit should be directly electrically connected to the electrical power system, so a device in the power conversion circuit, which is directly electrically connected to the electrical power system, should endure an alternating voltage ranging from 100 volts to 240 volts. A high-voltage semiconductor device can serve as the device in the power conversion circuit, which is directly electrically connected to the electrical power system, and is widely applied to the power conversion circuit in electrical devices, such as CPU power supplies, power management systems, AC/DC converters, LCDs and plasma television drivers, automobile electronic components, computer peripheral devices, small DC motor controllers, and lighting systems, etc., due to being capable of enduring the high voltage provided by the electrical power system and having switching characterize together. However, electrostatic discharge event easily occurs in the input end of the power conversion circuit that is directly electrically connected to the electrical power system, and the static charges enter into the internal circuit through the power conversion circuit, so that the internal circuit would be damaged by the static charges, and the electrical device malfunctions.
As a result, to prevent the internal circuit of the electrical device from being damaged by the ESD event generated from the input pad is an important objective in this field.